Radio communication systems are known to include a radio communication infrastructure and mobile or portable communication devices. Some systems (e.g., cellular systems) primarily support telephone communications, while other systems (e.g., trunked or conventional systems) primarily support dispatch communications. Some systems, such as Motorola's "iDEN" system, provide multiple services, such as telephone, dispatch, data, and short message, all in a single communications platform.
Regardless of the type of system, radio users in the system occasionally need to attend meetings or be in other situations in which they do not wish to be disturbed or interrupted. Cellular systems and normal wireline telephone systems accommodate such desires by providing voice mail service to their users. However, such is currently not the case in dispatch systems. In a dispatch system, when a user wants to be uninterrupted, the user must turn off his or her radio, or mute the audio. Although such action by the user allows him or her to remain undisturbed, the action does nothing to inform the callers that he or she is active in the system, but cannot respond at the moment.
In a dispatch system, when a user turns off his or her radio and another user attempts to contact him or her, the calling user receives a message from the radio communication infrastructure, such as "TARGET NOT AVAILABLE." Such a message is indeterminate because it could mean that the called device is powered off or it could mean that the called device is powered on, but simply out of the system coverage area. Accordingly, since the user of the calling device does not know the exact status of the called device, the user of the calling device continues to attempt to contact the user of the called device. Such retries are an inefficient use of system resources when the called user's intent was to remain undisturbed anyway.
Therefore, a need exists for a communication device and method for determining an operational status thereof that permits the communication device to remain active in the system at all times and that provides determinate feedback to calling device users that are attempting to contact the communication device at times when a user of the communication device does not wish to be disturbed.